The present invention relates generally to a non-return valve such as that used on a pneumatic tyre, and a membrane being permeable in one direction only. The invention further relates to a pressure relief valve and various forms of a high pressure non-return valve.
Non-return valves are common in industrial and domestic applications and are particularly prolific on pneumatic tyres. FIG. 1 illustrates the various components of a conventional pneumatic non-return valve 1. The valve 1 comprises an inlet casing 2 which is screw threaded within a valve stem of a tyre (not shown). The inlet casing 2 houses a shaft 3 along which a valve member 4 slidably moves. The valve member 4 is biased against a seat 5 of the casing 2 under the force of a compression spring 6 so as to close the valve 1. A spring retainer 7 is connected to an end of the shaft 3 so as to retain the compression spring 6. Pressurisation of the non-return valve 1 releases the valve member 4 from the seat 5 to allow filling of the tyre.
The conventional pneumatic non-return valve 1 suffers from at least the following problems:
i) the valve 1 has a relatively large number of components which may require periodic servicing and maintenance;
ii) the valve 1 is expensive including relatively complex machined components; and
iii) the valve is complicated in operation and thus in operation may be susceptible to failure.
The patent literature includes a myriad of patent specifications relating to valves, and in particular non-return valves, of a xe2x80x9cduck billxe2x80x9d configuration. For example, U.S. Pat. No. 3,822,720 describes an integral one piece valve moulded from a plastics material and including a hollow cylindrical main body within which a pair of lip members are integrally formed. The lip members are of the duck bill configuration which ordinarily are sealed together at their terminal end and open under pressure to permit flow in one direction whilst the main body may be squeezed inward to vent the valve and permit flow in an opposite direction. The valves of WO83/02320 and WO98/01689 are similarly of a duck bill configuration which is opened by an increase in pressure on an upstream or large cross sectional area of the duck bill valves. The non-return valves of this configuration are generally automatically closed by the resilient stresses in the duck bill membranes.
Although relatively simple in construction these duck bill valves of the prior art have at least the following drawbacks:
i) the valves are relatively unreliable and may leak across the aperture of the opening of the duck bill;
ii) the duck bill valve is susceptible to contamination with foreign/solid particles which may cause valve leakage; and
iii) the valve is not symmetrical about its axis which may result in difficulties in tooling and moulding, and the asymmetric nature of the valve may result in leakage particularly at relatively high pressures.
According to one aspect of the present invention there is provided a non-return valve comprising:
a valve body including a fluid passageway which defines a fluid inlet and a fluid outlet located on a low pressure and a high pressure side of the valve, respectively, the fluid passageway being adapted to allow a flow of fluid from the inlet to the outlet; and
a valve diaphragm in the form of a conical-shaped diaphragm having a collapsible aperture located at or adjacent its apex which is oriented in a downstream flow direction and directed toward the high pressure side of the valve, said diaphragm being connected across the fluid passageway and being constructed of a resiliently flexible material wherein the diaphragm itself initiates closure of the collapsible aperture, said closure being further promoted by fluid on the high pressure side of the valve to thus prevent fluid flowing in a reverse direction toward the inlet whereas the application of pressure, exceeding atmospheric pressure and that on the high pressure side, to an inlet side of the diaphragm deflects the diaphragm to expose the aperture and allow fluid to flow through the passageway from the inlet to the outlet only.
Typically the pressure is imposed on the inlet side of the diaphragm via a fluid nozzle which is designed to be retractably received within the passageway. Alternatively the diaphragm is deflected by fluid pressure on the low pressure side of the diaphragm which exceeds that on the high pressure side thereby exposing the collapsible aperture.
Generally the fluid is a liquid such as petrol and the non-return valve serves to prevent a reverse flow or escape of vapours.
Preferably the valve body is designed to fit to a reservoir or tank in which fluid is to be dispensed via the fluid nozzle. For example, the non-return valve is configured to fit to a petrol tank.
According to a further aspect of the present invention there is provided a non-return valve including a bank or series of non-return valves of similar construction coupled to one another, each of said non-return valves comprising:
a valve body including a fluid passageway which defines a fluid inlet and a fluid outlet, the fluid passageway being adapted to allow a flow of fluid from the inlet to the outlet; and
a valve diaphragm being connected across the fluid passageway and including a collapsible aperture, the valve diaphragm being constructed of a resiliently flexible material and being configured wherein the diaphragm itself in a collapsed condition effects closure of the collapsible aperture to prevent fluid flowing in a reverse direction toward the inlet whereas pressure imposed on an inlet side of the diaphragm deflects the diaphragm to expose the aperture and allow fluid to flow through the passageway from the inlet to the outlet only.
Generally the non-return valves are coupled together with their respective valve bodies at least partly nested within one another wherein said valves are co-axially aligned. Alternatively the non-return valves are each of the same construction and configured to abut or engage one another with their valve bodies in alignment.
Preferably each of the diaphragms is formed integral with the corresponding valve body. More preferably the diaphragms are each in the form of a generally conical-shaped diaphragm having the collapsible aperture located at or adjacent its apex which is oriented in a downstream flow direction.
Generally said actuating means is a fluid nozzle which is retractably inserted into at least one of the collapsible apertures to permit a flow of fluid across the corresponding diaphragm via the fluid nozzle.
Preferably the valve diaphragm is formed integral with the valve body.
Typically the valve diaphragm is constructed of a mouldable polymeric material. More typically the polymeric material is an elastomer such as a rubber material. Alternatively the polymeric material is a nylon-based material.
Preferably the valve body is configured to retrofit to an existing valve stem. Alternatively the valve body is designed to be sealably inserted into a flow line.
Generally the fluid is water or compressed air.
According to yet a further aspect of the present invention there is provided a membrane being permeable in one direction only, said membrane comprising a panel or blanket of collapsible diaphragms each including a collapsible aperture and being constructed of a resiliently flexible material which is configured wherein each of the diaphragms themselves effects closure of the collapsible aperture to prevent fluid flowing in a reverse direction whereas pressure imposed on an upstream side of the membrane deflects one or more of the diaphragms to expose the corresponding aperture and allow fluid to flow across the membrane in said one direction only.
Generally the membrane is multi-layered with a series of said panels or blankets formed adjacent one another.
According to another aspect of the invention there is provided a non-return valve comprising:
a valve body including a fluid passageway which defines a fluid inlet and a fluid outlet, the fluid passageway being adapted to allow a flow of fluid from the inlet to the outlet;
a valve diaphragm being connected across the fluid passageway and including a collapsible aperture, said diaphragm being constructed of a resiliently flexible material and being configured wherein the diaphragm initiates closure of the collapsible aperture to prevent fluid flowing in a reverse direction toward the inlet; and
a valve actuator connected to the diaphragm and being configured wherein axial movement of the actuator toward the fluid outlet deflects the diaphragm to expose the aperture and allow fluid to flow through the passageway from the inlet to the outlet only.
Preferably the diaphragm is in the form of a generally conical-shaped diaphragm having the collapsible aperture located at or adjacent its apex which is orientated in a downstream flow direction.
Preferably the valve actuator includes an elongate member formed integral and generally coaxial with the conical-shaped valve diaphragm. Alternatively the valve actuator includes an elongate member having at one end an engaging surface being configured to abut the diaphragm at its inlet side.
Preferably the valve actuator also includes a retaining element coupled to the elongate member and configured to operatively engage the valve body to inhibit axial displacement of the elongate member and its engaging surface and thus deflection of the diaphragm under pressure.
Preferably the collapsible aperture is in the form of one or more slits each being formed through an axis of the valve.
According to yet another aspect of the invention there is provided a pressure relief valve comprising:
a valve body including a fluid passageway which defines a fluid inlet and a fluid outlet located on a low pressure and a high pressure side of the valve respectively; and
a valve diaphragm in the form of a conical-shaped diaphragm having a collapsible aperture located at or adjacent its apex which is oriented in a downstream flow direction and directed toward the high pressure side of the valve, said diaphragm being connected across the fluid passageway and being constructed of a resiliently flexible material wherein the diaphragm initiates closure of the collapsible aperture, the diaphragm being configured whereby excessive pressure on the high pressure side of the valve effects deflection of the diaphragm to expose the collapsible aperture to temporarily vent fluid from said high pressure side.
Preferably the collapsible aperture is in the form of one or more slits each being formed through an axis of the valve and its conical-shaped diaphragm.
According to still a further aspect of the invention there is provided a high pressure non-return valve comprising:
a valve body including a fluid passageway which defines a fluid inlet and a fluid outlet located on a low pressure and a high pressure side of the valve respectively;
a valve diaphragm being connected across the fluid passageway and including a collapsible aperture, said diaphragm being constructed of a resiliently flexible material and being configured wherein pressure imposed on the high pressure side of the valve promotes closure of the collapsible aperture to prevent fluid flowing in a reverse direction toward the inlet; and
a reinforcing member being disposed across the valve body and designed to operatively engage the diaphragm on its low pressure side whereby the reinforcing member restricts deflection of the diaphragm when a relatively high pressure is applied on the high pressure side of the diaphragm thus maintaining closure of the collapsible aperture and the valve.
Preferably the valve diaphragm is generally conical-shaped having its apex directed to the outlet and the high pressure side of the valve.
More preferably the reinforcing member is conical-shaped and configured to nest within the fluid passageway adjacent the diaphragm on its inlet side.
In this embodiment the conical-shaped member includes a plurality of fluid openings to permit the passage of fluid.